Key Points:

  • A tsunami has struck the Indonesian island of Sulawesi following a major 7.5-magnitude earthquake.
  • Buildings have collapsed and homes have been washed away.
  • 'Several' people dead, say authorities
  • A tsunami warning was in place โ€“ but then lifted before the wave struck
  • Officials say waters have receded, but families are still missing.

A powerful earthquake rocked the Indonesian island of Sulawesi on Friday, triggering a 3m tall tsunami that an official said swept away houses in at least two cities.

Disaster agency spokesman Sutopo Purwo Nugroho said the tsunami hit Palu, the capital of central Sulawesi province, as well as the smaller city of Donggala and several other coastal settlements.

Indonesian TV showed a smartphone video of a powerful wave hitting Palu, with people screaming and running in fear. The water smashed into buildings and a large mosque that collapsed under the force.

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Houses were swept away and families were reported missing, Nugroho said, adding that communications and power to the area were disrupted.

"The cut to telecommunications and darkness are hampering efforts to obtain information," he said. "All national potential will be deployed, and tomorrow morning we will deploy Hercules and helicopters to provide assistance in tsunami-affected areas."

Sky TV's Siobhan Robins reports, warnings were issued before the tsunami hit.

"The big question now is how many people were still in their houses when those waves crashed onto the shore... And how many had actually made it to safer ground."

Officials have asked people to remain on the alert amid a series of moderate aftershocks.

"We advise people to remain in safe areas, stay away from damaged buildings," Sutopo Purwo Nugroho, spokesman for the National Disaster Mitigation Agency, said.

The agency was having difficulties reaching some authorities in the fishing town of Donggala and Palu city, the capital of central Sulawesi province, closest to the epicentre of the quake 80km away at a shallow 10km underground.

Palu airport was closed.

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The US Geological Survey put the magnitude of the second quake at a strong 7.5, after first saying it was 7.7.

The earlier quake destroyed some houses, killing one person and injuring at least 10 in Donggala, authorities said.

More than 600,000 people live in Donggala and Palu.

"The (second) quake was felt very strongly, we expect more damage and more victims," Nugroho said, adding that evacuation process is still ongoing.

A series of earthquakes in July and August killed nearly 500 people on the holiday island of Lombok, hundreds of kilometres southwest of Sulawesi.


- with AP